Early successes by primary challengers for two Republican Senate incumbents, Dick Lugar in Indiana and Orrin Hatch in Utah, have reminded the country that the Tea Party still represents an important force. But as with many political movements, it’s fair to ask whether the tea-party movement itself, with its massive rallies and various affiliated organizations, has really been the distinguishing factor, or whether the U.S. was due for a surge in conservative activism and anti-incumbent sentiment anyway.
So, did the Tea Party qua Tea Party matter? In a recent paper, four political-science graduate students, from Harvard and Italy’s Bocconi University, claim to have found the answer: Yes, quite a bit.
Holding other factors like the degree of conservatism potential of an area constant, if April 15, 2009, was sunny in a particular place, the rally would be better attended, and much worse attended if it were rainy — and if areas that randomly received better turnout because of the weather ended up more conservative, then the tea-party rallies themselves mattered, and encouraged lasting political activity and change, above and beyond the other factors that might have encouraged conservative activism.
It turns out the difference was dramatic: Representatives of congressional districts where rally attendance was dampened by rain had American Conservative Union ratings over the following two years that were 9 to 12 points more liberal (lower, on a 100-point scale). Members of Congress from districts where rain lowered attendance for tea-party rallies were, for instance, 8.7 percent more likely to vote for Obamacare (the authors note that, if one makes a suggestive counterfactual based on this number, if it had been sunny everywhere in America on April 15, 2009, the bill would have been defeated 217–218). One additional protester showing up at a tea-party rally on that date, controlling for all other factors, resulted in an extra 7 to 14 Republican votes.